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Using only the heating of an old combination boiler?

igorjadigorjad Posts: 4Member
Hello all!

I have an old (circa 1960 when the house was built) Arcoleader A14P oil boiler that provides baseboard heat and DHW. The coil is leaking, but the rest seems intact at this point. The service technician thinks it's unlikely to be able find a replacement coil. We don't use much oil (~700-750 gallons/year), so replacing the entire boiler is not particularly cost effective. Is it possible to use the boiler for heating only by simply bypassing the DHW coil (we're thinking of installing a tankless electric water heater in place of that)? If so, is there a particular way to go about the bypass, or could I just cut and cap the inlet & outlet piping? Thanks in advance!

Comments

  • SteamheadSteamhead Posts: 13,220Member
    If the coil is leaking, it'll have to be capped.

    No natural gas service to your house?
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • igorjadigorjad Posts: 4Member
    No lines, but we can get gas delivered. But then we'd have to deal with the cost of converting and replacing the boiler, which is what we're trying to avoid at this point.
  • HVACNUTHVACNUT Posts: 2,422Member
    Does it at least have a modern burner? This is an internal leak? Not the plate and gasket? Diversified Heat Transfer Products has a coil for that boiler but that might be opening a can of worms. 50 yr old bolts like to snap. Then its drill and tap time. If you wind up capping the hot and cold on the coil, I would recommend a Shark Bite cap on one pipe. Make sure the coil is full of water before you cap it. You dont want steam forming in the coil.
    On the other hand, if the bolts are forgiving, then it can be removed, cut the coil from the plate and reinstall the plate only with a new gasket. Then plug the hot and cold. Keep in mind, sooner or later there will be an issue where a repair is not cost effective. And it usually happens in February, during a blizzard. Plan for the worst. Hope for the best.
  • retiredguyretiredguy Posts: 69Member
    edited October 12
    Removing the nuts from the coil plate can usually be accomplished by soaking them with a penetrating oil (PB Blaster, Liquid wrench or any other) over a period of time. I have removed bolts, nuts and pipe plugs by spraying these daily for several weeks. Then using a wrench try to tighten the bolt or nut, ever so slightly to break the hold of the "grip of time". By tightening, the resistance to turning is reduced slightly since the strain on the bolt/nut is in the tightening motionor direction. A slight movement may sometimes break the hold that "time" has put on the bolt/nut and make removal without breakage possible. Depending on the type of coil, and the condition of the coil a good rad shop can sometimes repair a leaking coil. A good service tech may also be able to repair the coil. Or as @HVACNUT stated Diversified Heat Transfer Products has a coil for that boiler.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,967Member
    Abandoning the dhw coil and making the boiler a cold start after 60 years may not be a good idea....it could start leaking.

    If the coil bolts cant be removed to install a new coil you could install a small heat exchanger for dhw and "external tankless heater" Everhot makes them
  • Danny ScullyDanny Scully Posts: 1,207Member
    To clarify what @Steamhead means (or at least what I think he means), “capping” the coil would involve removing the coil and installing a blank coil plate. If you simple cap the existing coil, you’re essentially creating a bomb. Now I suppose the coil could be leaking into the boiler, although that’s not clear from your description.
  • SteamheadSteamhead Posts: 13,220Member

    To clarify what @Steamhead means (or at least what I think he means), “capping” the coil would involve removing the coil and installing a blank coil plate. If you simple cap the existing coil, you’re essentially creating a bomb. Now I suppose the coil could be leaking into the boiler, although that’s not clear from your description.

    If the coil is leaking, pressure cannot build up in it. But the safer way is to remove at least part of the coil and cap the openings in the plate.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • STEVEusaPASTEVEusaPA Posts: 3,186Member
    edited October 12
    You can find a coil for it. I have the link to a place online on my office computer I can post later.
    And with the amount of water in that boiler you’ll have plenty of hot water.
    Efficiency is poor, and you’re wasting oil keeping that boiler hot.
    Follow the advice for others about removing the bolts.

    Edit: here’s one:
    https://www.oswaldsupply.com/boilers-heating-supplies/domestic-hot-water/tankless-coils.html
    steve
  • igorjadigorjad Posts: 4Member
    Thanks all fro your input! To clarify some:

    @HVACNUT : It does have a modern Carlin burner, and the nozzles were replaced ~1 year ago.

    The coil is leaking along the outside of the unit, but we don't know the exact extent of the leak because the service tech did not attempt to remove the old coil for fear of opening up that can of worms until we are prepared to do something about it.

    I understand and completely agree that at some point repair is not going be cost effective (and that point may be now). I'm not too worried about keeping the house warm (we've got 2 stoves and mini-splits), but we do need DHW.

    @retiredguy : Agree with all of that, thank you!

    @EBEBRATT-Ed : Could you expand on why it might start leaking if there's no other corrosion or damage? I don't know what cold start implies.

    @Danny Scully & @Steamhead : Understood, thank you!

    @STEVEusaPA : Yes, my thinking is that the efficiency on this thing is poor (at best!), but given the amount of oil we use (which should be less now that we've installed the mini-splits), ROI on a new boiler will be lengthy, which is why we're trying to avoid it.
  • Intplm.Intplm. Posts: 861Member
    I'm sorry to say, but it is time to change the boiler. Attempting a repair is not cost effective.
    You might just find that the amount of work needed to fix this leak could come close to a new boiler price in the long run.
    Not to mention the headaches you may need to endure along the way.
    Always a bummer when this happens.
  • igorjadigorjad Posts: 4Member
    Appreciate all the comments, will let you know what we end up doing!
  • retiredguyretiredguy Posts: 69Member
    If you just want to cap the coil that will work. You will not have a "bomb" since the pressure in the coil can not be above the pressure for the temperature of the surrounding water. (consult a steam temperature pressure table).
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